Golf ball resin composition and golf ball using the same

ABSTRACT

An object of the present invention is to provide a golf ball traveling a great flight distance on driver shots and a golf ball resin composition. The present invention provides a golf ball wherein at least one constituting member therefore is formed from a golf ball resin composition containing: (A) a polyamide resin, (B) at least one member selected from the group consisting of (b-1) a binary copolymer composed of an olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (b-2) a metal ion-neutralized product of a binary copolymer composed of an olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (b-3) a ternary copolymer composed of an olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturated carboxylic acid ester, and (b-4) a metal ion-neutralized product of a ternary copolymer composed of an olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturated carboxylic acid ester, and (C) an organically modified layered silicate, wherein a mass ratio ((A)/(B)) of (A) component to (B) component ranges from 15/85 to 80/20.

FIELD OF THE INVENTION

The present invention relates to a golf ball resin composition havinghigh resilience and a golf ball travelling a great flight distance ondriver shots.

DESCRIPTION OF THE RELATED ART

As a three-piece golf ball or a multi-piece golf ball, a golf ballemploying a highly rigid or highly elastic intermediate layer has beenproposed.

For example, Japanese Patent Publication No. 2010-17414 A discloses agolf ball comprising a core consisting of a center and one or moreintermediate layers covering the center, and a cover covering the core,wherein at least one piece or one layer of the intermediate layers isformed from a highly elastic intermediate layer composition containing:(A) a highly elastic polyamide resin having a flexural modulus of 700MPa to 5000 MPa, (B) a metal-neutralized product of anethylene-(meth)acrylic acid copolymer, and (C) a resin having a polarfunctional group, a content ratio (total:100 mass %) of (A) the highlyelastic polyamide resin to (B) the metal-neutralized product of theethylene-(meth)acrylic acid copolymer is (A) highly elastic polyamideresin/(B) metal-neutralized product of ethylene-(meth)acrylic acidcopolymer=20 mass % to 80 mass %/80 mass % to 20 mass %, and the contentof (C) the resin having the polar functional group is 0.1 part by massto 20 parts by mass with respect to a total of 100 parts by mass of (A)the highly elastic polyamide resin and (B) the metal-neutralized productof the ethylene-(meth)acrylic acid copolymer.

Japanese Patent Publication No. 2009-261791 A discloses a golf ballcomprising a core consisting of a center and one or more intermediatelayers covering the center, and a cover covering the core, wherein atleast one piece or one layer of the intermediate layers is formed from ahighly elastic intermediate layer composition containing: (A) a highlyelastic resin having a flexural modulus of 700 MPa to 5000 MPa and (B)an ionomer resin having a flexural modulus of 150 MPa to 1000 MPa, and acontent ratio (total:100 mass %) of (A) the highly elastic resin to (B)the ionomer resin is (A) highly elastic resin/(B) ionomer resin=20 mass% to 80 mass %/80 mass % to 20 mass %.

Japanese Patent Publication No. 2009-261792 A discloses a golf ballcomprising a core consisting of a center and one or more intermediatelayers covering the center, and a cover covering the core, wherein atleast one piece or one layer of the intermediate layers is formed from ahighly rigid intermediate layer composition containing, as a resincomponent, (a) an ethylene-(meth)acrylic acid copolymer or ametal-neutralized product thereof, (b) a copolymer composed of anα-olefin and a glycidyl (meth)acrylate or a glycidyl unsaturated ether,(c) a polyolefin, and (d) an ionomer resin neutralized with a metalspecies different from that used for (a) the metal-neutralized productof the ethylene-(meth)acrylic acid copolymer, a mass ratio ((a+b+c)/d)of a total mass (a+b+c) of (a) the ethylene-(meth)acrylic acid copolymeror the metal-neutralized product thereof, (b) the copolymer composed ofthe α-olefin and the glycidyl (meth)acrylate or the glycidyl unsaturatedether, and (c) the polyolefin, to a mass of (d) the ionomer resinneutralized with the metal species different from that used for (a) themetal-neutralized product of the ethylene-(meth)acrylic acid copolymerin the resin component is 95 parts by mass/5 parts by mass to 50 partsby mass/50 parts by mass.

Japanese Patent Publication No. 2000-119516 A discloses a polyamideresin composition obtained by melting and kneading (A) a polyamide resinand (B) a layered silicate so as to the inorganic ash content in thecomposition being 0.1 to 50 wt %, wherein 40% or more of the total aminoterminal groups in the polyamide resin form an ionic bond with thelayered silicate in the composition.

Japanese Patent Publication No. 2004-509200 A discloses apolymer-organic clay composite composition containing the following (A),(B), (C), (D), and (E):

-   (A) one or more types of organic thermoplastic polymers having an    amine group;-   (B) one or more types of organic clays containing an organic    ammonium cation having a specific structure, and existing in an    amount of approximately 0.1 wt % to approximately 40 wt % based on    the total weight of the components (A), (B), (C), (D), and (E);-   (C) a thermoplastic resin different from the component (A), and    existing in an amount of approximately 0.0 to approximately 90 wt %    based on the total weight of the components (A), (B), (C), (D), and    (E);-   (D) an impact modifier existing in an amount of approximately 0 to    approximately 20 wt % based on the total weight of the components    (A), (B), (C), (D), and (E); and-   (E) a compatibilizer existing in an amount of approximately 0 to    approximately 10 wt % based on the total weight of the components    (A), (B), (C), (D), and (E).

Japanese Patent Publication No. 2011-15763 A discloses a golf ball resincomposition containing: at least one type selected from a zincion-neutralized ionomer resin and a sodium ion-neutralized ionomer resinas an ionomer resin component, at least one type selected from apolyamide and a polyetheramine as a dispersant, and a clay, providedthat the golf ball resin composition contains the polyamide as thedispersant in the case of containing the zinc ion-neutralized ionomerresin as the ionomer resin component, and contains the polyetheramine asthe dispersant in the case of containing the sodium ion-neutralizedionomer resin.

SUMMARY OF THE INVENTION

One of the major demands for a golf ball is to improve its flightdistance. As a method for improving a flight distance of a golf ball, amethod using a highly rigid or highly elastic material is known. Amongthe highly rigid or highly elastic materials, a material that providesan even greater flight distance is desired.

The present invention has been made in view of the above describedsituation, and an object of the present invention is to provide a highresilience material which provides an even greater flight distance.Another object of the present invention is to provide a golf balltraveling a great flight distance on driver shots.

The golf ball resin composition of the present invention which can solvethe above problem comprises: (A) a polyamide resin, (B) at least onemember selected from the group consisting of (b-1) a binary copolymercomposed of an olefin and an α,β-unsaturated carboxylic acid having 3 to8 carbon atoms, (b-2) a metal ion-neutralized product of a binarycopolymer composed of an olefin and an α,β-unsaturated carboxylic acidhaving 3 to 8 carbon atoms, (b-3) a ternary copolymer composed of anolefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atomsand an α,β-unsaturated carboxylic acid ester, and (b-4) a metalion-neutralized product of a ternary copolymer composed of an olefin, anα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and anα,β-unsaturated carboxylic acid ester, and (C) an organically modifiedlayered silicate, wherein a mass ratio ((A)/(B)) of (A) component to (B)component ranges from 15/85 to 80/20.

The golf ball resin composition of the present invention has highresilience by containing (A) component, (B) component and (C) component.As a result, the golf ball using the golf ball resin composition of thepresent invention travels a great flight distance on driver shots.

The present invention includes a golf ball comprising a core, at leastone intermediate layer covering the core, and a cover covering theintermediate layer, wherein at least one constituting member selectedfrom the core, at least one intermediate layer and the cover is formedfrom the golf ball resin composition of the present invention.

According to the present invention, a golf ball travelling a greatflight distance on driver shots is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of dimple patterns formed on the surface of thegolf ball; and

FIG. 2 is a plan view of dimple patterns formed on the surface of thegolf ball.

DESCRIPTION OF THE PREFERRED EMBODIMENT

(1) Golf Ball Resin Composition

The golf ball resin composition of the present invention comprises: (A)a polyamide resin, (B) at least one member selected from the groupconsisting of (b-1) a binary copolymer composed of an olefin and anα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (b-2) ametal ion-neutralized product of a binary copolymer composed of anolefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbonatoms, (b-3) a ternary copolymer composed of an olefin, anα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and anα,β-unsaturated carboxylic acid ester, and (b-4) a metal ion-neutralizedproduct of a ternary copolymer composed of an olefin, an α,β-unsaturatedcarboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturatedcarboxylic acid ester, and (C) an organically modified layered silicate,wherein a mass ratio ((A)/(B)) of (A) component to (B) component rangesfrom 15/85 to 80/20.

Firstly, (A) the polyamide resin used in the present invention will beexplained. (A) The polyamide resin is not particularly limited as longas it is a polymer having multiple amide bonds (—NH—CO—) in the mainchain. Examples of the polyamide resin include products having amidebonds formed in the molecule through ring-opening polymerization of alactam, a condensation reaction of amino acids, or a condensationreaction between a diamine component and a dicarboxylic acid component.

Examples of the lactam include ε-caprolactam, undecane lactam, andlauryl lactam. Examples of the amino acid include 6-aminocaproic acid,11-aminoundecanoic acid, 12-aminododecanoic acid, andpara-aminomethylbenzoic acid.

Examples of the diamine component include aliphatic diamines such astetramethylene diamine, hexamethylene diamine, 2-methyl pentamethylenediamine, undecamethylene diamine, dodecamethylene diamine,2,2,4-/2,4,4-trimethyl hexamethylene diamine, and 5-methyl nonamethylenediamine; aromatic diamines such as meta-xylylene diamine andpara-xylylene diamine; and alicyclic diamines such as1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane,1-amino-3-aminomethyl-3,5,5-trimethyl cyclohexane,bis(4-aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)methane,2,2-bis(4-aminocyclohexyl)propane, bis(aminopropyl)piperazine, andaminoethyl piperazine.

Examples of the dicarboxylic acid component include aliphaticdicarboxylic acids such as adipic acid, suberic acid, azelaic acid,sebacic acid, and dodecanedioic acid; aromatic dicarboxylic acids suchas terephthalic acid, isophthalic acid, 2-chloroterephthalic acid,2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodiumsulfoisophthalic acid, hexahydroterephthalic acid, andhexahydroisophthalic acid; and alicyclic dicarboxylic acids such as1,4-cyclohexanedicarboxylic acid.

Examples of (A) the polyamide resin include aliphatic polyamides such asPolyamide 6, Polyamide 11, Polyamide 12, Polyamide 66, Polyamide 610,and Polyamide 612; semi-aromatic polyamides such as Polyamide 6T,Polyamide 6I, Polyamide 9T, and Polyamide M5T; and aromatic polyamidessuch as poly-p-phenylene terephthalamide and poly-m-phenyleneisophthalamide. Those polyamide resins may be used solely or in acombination of two or more. Among them, from a standpoint ofprocessability and durability, the aliphatic polyamide such as Polyamide6, Polyamide 66, Polyamide 11, and Polyamide 12 is suitable.

Specific examples of the polyamide resin in terms of trade namesinclude: “Rilsan (Registered trademark) B (e.g., BESN TL, BESN P20 TL,BESN P40 TL, MB3610, BMF O, BMN O, BMN O TLD, BMN BK TLD, BMN P20 D, andBMN P40 D, etc.)” commercially available from Arkema K. K.; “Novamid(Registered trademark) (e.g., 1010C2, 1011 CHS, 1013C5, 1010N2,1010N2-2, 1010N2-1ES, 1013G(H)10-1, 1013G(H)15-1, 1013G(H)20-1,1013G(H)30-1, 1013(H)45-1, 1015G33, 1015GH35, 1015GSTH, 1010GN2-30,1015F2, ST220, ST145, 3010SR, 3010N5-SL4, 3021G(H)30, 3010GN30, etc.)”commercially available from DSM Engineering Plastics Inc.; and “Amilan(Registered trademark) (e.g., CM1007, CM1017, CM1017XL3, CM1017K,CM1026, CM3007, CM3001-N, CM3006, CM3301 L, etc.)” manufactured by TorayIndustries Inc.

The melt flow rate (260° C., 325 g) of the polyamide resin measured inaccordance with a method of ISO113 is preferably 5 g/min or more, morepreferably 8 g/min or more, even more preferably 20 g/min or more, andis preferably 170 g/min or less, more preferably 150 g/10 min or less,even more preferably 120 g/10 min or less. If the melt flow rate (260°C., 325 g) of the polyamide resin is 5 g/10 min or more, fluiditybecomes better, thus molding the polyamide resin into the constitutingmember of the golf ball becomes easier. In addition, if the melt flowrate (260° C., 325 g) of the polyamide resin is 170 g/10 min or less,durability of the resultant golf ball becomes better.

The flexural modulus of the polyamide resin measured in accordance witha method of ISO178 is preferably 500 MPa or more, more preferably 520MPa or more, even more preferably 550 MPa or more, and is preferably4,000 MPa or less, more preferably 3,500 MPa or less, even morepreferably 3,200 MPa or less. If the flexural modulus of the polyamideresin is 500 MPa or more, the constituting member of the resultant golfball has high resilience. As a result, the initial speed of the golfball becomes high. In addition, if the flexural modulus of (A) thepolyamide resin is 4,000 MPa or less, the constituting member of theresultant golf ball does not become excessively hard, thus excellentshot feeling and durability are obtained.

Although the degree of polymerization of the polyamide resin is notparticularly limited, the relative viscosity of the polyamide resinmeasured in accordance with a method of ISO307 is preferably in a rangeof 1.5 to 5.0, and more preferably in a range of 2.0 to 4.0.

As the polyamide resin, for example, a polyamide resin havingcrystalline state and amorphous state in a coexisting manner ispreferable. In this case, the degree of crystallinity of the polyamideresin is preferably 5% or more, more preferably 6% or more, even morepreferably 6.5% or more, and is preferably 15% or less, more preferably14% or less, even more preferably 13% or less. The degree ofcrystallinity X can be calculated from the following expression;X=[dc(d−da)]/[d(dc−da)]herein, dc: density of crystalline state, da: density of amorphousstate, d: density of sample.

Next, (B) component used in the present invention will be explained. Thegolf ball resin composition of the present invention contains (B) atleast one member selected from the group consisting of (b-1) a binarycopolymer composed of an olefin and an α,β-unsaturated carboxylic acidhaving 3 to 8 carbon atoms, (b-2) a metal ion-neutralized product of abinary copolymer composed of an olefin and an α,β-unsaturated carboxylicacid having 3 to 8 carbon atoms, (b-3) a ternary copolymer composed ofan olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atomsand an α,β-unsaturated carboxylic acid ester, and (b-4) a metalion-neutralized product of a ternary copolymer composed of an olefin, anα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and anα,β-unsaturated carboxylic acid ester.

(b-1) component is a nonionic binary copolymer composed of an olefin andan α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms whereincarboxyl groups thereof are not neutralized. Further, (b-2) componentincludes an ionomer resin prepared by neutralizing at least a part ofcarboxyl groups in a binary copolymer composed of an olefin andα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms with a metalion.

(b-3) component is a nonionic ternary copolymer composed of an olefin,an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and anα,β-unsaturated carboxylic acid ester wherein carboxyl groups thereofare not neutralized. Further, (b-4) component includes an ionomer resinprepared by neutralizing at least a part of carboxyl groups in a ternarycopolymer composed of an olefin, α,β-unsaturated carboxylic acid having3 to 8 carbon atoms and an α,β-unsaturated carboxylic acid ester with ametal ion.

In the present invention, “(b-1) the binary copolymer composed of anolefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbonatoms” is sometimes merely referred to as “binary copolymer”, “(b-2) themetal ion-neutralized product of a binary copolymer composed of anolefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbonatoms” is sometimes merely referred to as “binary ionomer resin”, “(b-3)the ternary copolymer composed of an olefin, an α,β-unsaturatedcarboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturatedcarboxylic acid ester” is sometimes merely referred to as “ternarycopolymer”, and “(b-4) the metal ion-neutralized product of a ternarycopolymer composed of an olefin, an α,β-unsaturated carboxylic acidhaving 3 to 8 carbon atoms and an α,β-unsaturated carboxylic acid ester”is sometimes merely referred to as “ternary ionomer resin”.

The golf ball resin composition of the present invention preferablycontains (b-2) the binary ionomer resin and/or (b-4) the ternary ionomerresin as (B) component. In the case that the golf ball resin compositionof the present invention contains only (b-1) the binary copolymer and/or(b-3) the ternary copolymer as (B) component, the golf ball resincomposition preferably further contains a metal compound. Neutralizingthe carboxyl groups in (b-1) the binary copolymer and/or (b-3) theternary copolymer with the metal compound in the golf ball resincomposition provides substantially the same effect as using the binaryionomer resin and/or the ternary ionomer resin.

Examples of the metal compound used for neutralizing the carboxyl groupsof (b-1) the binary copolymer and/or (b-3) the ternary copolymerinclude, for example, metal hydroxides such as magnesium hydroxide, zinchydroxide, calcium hydroxide, sodium hydroxide, lithium hydroxide,potassium hydroxide, copper hydroxide, and the like; metal oxides suchas magnesium oxide, calcium oxide, zinc oxide, copper oxide, and thelike; metal carbonates such as magnesium carbonate, zinc carbonate,calcium carbonate, sodium carbonate, lithium carbonate, potassiumcarbonate, and the like.

The content of the α,β-unsaturated carboxylic acid having 3 to 8 carbonatoms in (B) component of the golf ball resin composition of the presentinvention is preferably 15 mass % or more, more preferably 16 mass % ormore, and even more preferably 17 mass % or more. If the content of theacid component is 15 mass % or more, the resultant golf ball resincomposition shows better resilience and hardness. The upper limit of thecontent of the α,β-unsaturated carboxylic acid having 3 to 8 carbonatoms is not particularly limited, but it is preferably 30 mass %, andmore preferably 25 mass %.

The olefin preferably includes an olefin having 2 to 8 carbon atoms.Examples of the olefin include ethylene, propylene, butene, pentene,hexene, heptene, octane and the like. The olefin more preferablyincludes ethylene. Examples of the α,β-unsaturated carboxylic acidhaving 3 to 8 carbon atoms are acrylic acid, methacrylic acid, fumaricacid, maleic acid, crotonic acid and the like. Among these, acrylic acidand methacrylic acid are particularly preferred. Examples of theα,β-unsaturated carboxylic acid ester include methyl ester, ethyl ester,propyl ester, n-butyl ester, isobutyl ester of acrylic acid, methacrylicacid, fumaric acid, maleic acid and the like. In particular, acrylicacid ester and methacrylic acid ester are preferable.

(b-1) The binary copolymer preferably includes a binary copolymercomposed of ethylene and (meth)acrylic acid. (b-2) The binary ionomerresin preferably includes a metal ion-neutralized product of a binarycopolymer composed of ethylene-(meth)acrylic acid. (b-3) The ternarycopolymer preferably includes a ternary copolymer composed of ethylene,(meth)acrylic acid and (meth)acrylic acid ester. (b-4) The ternaryionomer resin preferably includes a metal ion-neutralized product of aternary copolymer composed of ethylene, (meth)acrylic acid and(meth)acrylic acid ester. Here, (meth)acrylic acid means acrylic acidand/or methacrylic acid.

The content of the α,β-unsaturated carboxylic acid component having 3 to8 carbon atoms in (b-1) the binary copolymer or (b-3) the ternarycopolymer is preferably 4 mass % or more, more preferably 5 mass % ormore, and is preferably 30 mass % or less, more preferably 25 mass % orless.

The melt flow rate (190° C., 2.16 kgf) of (b-1) the binary copolymer or(b-3) the ternary copolymer is preferably 5 g/10 min or more, morepreferably 10 g/10 min or more, even more preferably 15 g/10 min ormore, and is preferably 1,700 g/10 min or less, more preferably 1,500g/10 min or less, even more preferably 1,300 g/10 min or less. If themelt flow rate (190° C., 2.16 kgf) of (b-1) the binary copolymer or(b-3) the ternary copolymer is 5 g/10 min or more, the golf ball resincomposition has better fluidity, and thus it is easier to mold a thinconstituent member. If the melt flow rate (190° C., 2.16 kgf) of (b-1)the binary copolymer or (b-3) the ternary copolymer is 1,700 g/10 min orless, the resultant golf ball has better durability.

Specific examples of (b-1) the binary copolymer include anethylene-methacrylic acid copolymer having a trade name of “NUCREL(registered trademark) (e.g. NUCREL N1050H, NUCREL N2050H, NUCRELAN4318, NUCREL N1110H, NUCREL N0200H)” commercially available from DuPont-Mitsui Polychemicals Co., Ltd. and an ethylene-acrylic acidcopolymer having a trade name of “PRIMACOR (registered trademark) 5980I”commercially available from Dow Chemical Company.

Specific examples of (b-3) the ternary copolymer include “NUCREL(registered trademark) (e.g. NUCREL AN4318, NUCREL AN4319)” commerciallyavailable from Du Pont-Mitsui Polychemicals Co., Ltd., “NUCREL(registered trademark) (e.g. NUCREL AE)” commercially available fromE.I. du Pont de Nemours and Company, and “PRIMACOR (registeredtrademark) (e.g. PRIMCOR AT310, PRIMCOR AT320)” commercially availablefrom Dow Chemical Company. (b-1) The binary copolymer or (b-3) theternary copolymer may be used alone or as a mixture of at least two ofthem.

The content of the α,β-unsaturated carboxylic acid component having 3 to8 carbon atoms in (b-2) the binary ionomer resin is preferably 15 mass %or more, more preferably 16 mass % or more, even more preferably 17 mass% or more, and is preferably 30 mass % or less, more preferably 25 mass% or less. If the content of the α,β-unsaturated carboxylic acidcomponent having 3 to 8 carbon atoms is 15 mass % or more, the resultantconstituent member has a desirable hardness. If the content of theα,β-unsaturated carboxylic acid component having 3 to 8 carbon atoms is30 mass % or less, since the hardness of the resultant constituentmember does not become excessively high, the durability and shot feelingbecome better.

The degree of neutralization of the carboxyl groups contained in (b-2)the binary ionomer resin is preferably 15 mole % or more, morepreferably 20 mole % or more, and is preferably 90 mole % or less, morepreferably 85 mole % or less. If the degree of neutralization is 15 mole% or more, the resultant golf ball has better resilience and durability.On the other hand, if the degree of neutralization is 90 mole % or less,the golf ball resin composition has better fluidity (good moldability).The degree of neutralization of the carboxyl groups contained in (b-2)the binary ionomer resin can be calculated by the following expression.Degree of neutralization (mole %) of the binary ionomer resin=(thenumber of moles of carboxyl groups neutralized in the binary ionomerresin/the number of moles of all carboxyl groups contained in the binaryionomer resin)×100

Examples of the metal ion used for neutralizing at least a part ofcarboxyl groups of (b-2) the binary ionomer resin include: monovalentmetal ions such as sodium, potassium, lithium and the like; divalentmetals ions such as magnesium, calcium, zinc, barium, cadmium and thelike; trivalent metals ions such as aluminum and the like; and otherions such as tin, zirconium and the like. As (b-2) the binary ionomerresin, a mixture of a binary ionomer resin neutralized with sodium and abinary ionomer resin neutralized with zinc is preferably used. By usingthe mixture, good resilience and durability can be obtained together.

Specific examples of (b-2) the binary ionomer resin include “Himilan(registered trademark) (e.g. Himilan 1555 (Na), Himilan 1557 (Zn),Himilan 1605 (Na), Himilan 1706 (Zn), Himilan 1707 (Na), Himilan AM7311(Mg), Himilan AM7329 (Zn))” commercially available from Du Pont-MitsuiPolychemicals Co., Ltd.

Further, examples include “Surlyn (registered trademark) (e.g. Surlyn8945 (Na), Surlyn 9945 (Zn), Surlyn 8140 (Na), Surlyn 8150 (Na), Surlyn9120 (Zn), Surlyn 9150 (Zn), Surlyn 6910 (Mg), Surlyn 6120 (Mg), Surlyn7930 (Li), Surlyn 7940 (Li), Surlyn AD8546 (Li))” commercially availablefrom E.I. du Pont de Nemours and Company.

Further, examples include “Iotek (registered trademark) (e.g. lotek 8000(Na), lotek 8030 (Na), lotek 7010 (Zn), lotek 7030 (Zn))” commerciallyavailable from ExxonMobil Chemical Corporation.

(b-2) The binary ionomer resins exemplified above may be used alone oras a mixture of at least two of them. It is noted that Na, Zn, Li, Mgand the like described in the parentheses after the trade names indicatemetal types of neutralizing metal ions of the binary ionomer resins.

(b-2) The binary ionomer resin preferably has a flexural modulus of 140MPa or more, more preferably 150 MPa or more, even more preferably 160MPa or more, and preferably has a flexural modulus of 550 MPa or less,more preferably 500 MPa or less, even more preferably 450 MPa or less.If the flexural modulus of (b-2) the binary ionomer resin falls withinthe above range, the flight performance of the resultant golf ball isexcellent because of the optimized spin rate on driver shots, and thedurability of the resultant golf ball becomes better.

(b-2) The binary ionomer resin preferably has a melt flow rate (190° C.,2.16 kgf) of 0.1 g/10 min or more, more preferably 0.5 g/10 min or more,even more preferably 1.0 g/10 min or more, and preferably has a meltflow rate (190° C., 2.16 kgf) of 30 g/10 min or less, more preferably 20g/10 min or less, even more preferably 15 g/10 min or less. If the meltflow rate (190° C., 2.16 kgf) of (b-2) the binary ionomer resin is 0.1g/10 min or more, the golf ball resin composition has better fluidityand thus, for example, it is possible to mold a thin constituent member.If the melt flow rate (190° C., 2.16 kgf) of (b-2) the binary ionomerresin is 30 g/10 min or less, the durability of the resultant golf ballbecomes better.

(b-2) The binary ionomer resin preferably has a slab hardness of 50 ormore, more preferably 55 or more, even more preferably 60 or more, andpreferably has a slab hardness of 75 or less, more preferably 73 orless, even more preferably 70 or less in Shore D hardness. If the binaryionomer resin has a slab hardness of 50 or more in Shore D hardness, theresultant constituent member has a high hardness. On the other hand, ifthe binary ionomer resin has a slab hardness of 75 or less in Shore Dhardness, the resultant constituent member does not become excessivelyhard, and thus the golf ball has better durability.

The content of the α,β-unsaturated carboxylic acid having 3 to 8 carbonatoms in (b-4) the ternary ionomer resin is preferably 2 mass % or more,more preferably 3 mass % or more, and is preferably 30 mass % or less,more preferably 25 mass % or less.

The degree of neutralization of the carboxyl groups contained in (b-4)the ternary ionomer resin is preferably 20 mole % or more, morepreferably 30 mole % or more, and is preferably 90 mole % or less, morepreferably 85 mole % or less. If the degree of neutralization is 20 mole% or more, the resultant golf ball obtained by using the golf ball resincomposition of the present invention has better resilience anddurability. If the degree of neutralization is 90 mole % or less, thegolf ball resin composition has better fluidity (good moldability). Thedegree of neutralization of the carboxyl groups in the ionomer resin canbe calculated by the following expression.Degree of neutralization (mole %) of the ionomer resin=(the number ofmoles of carboxyl groups neutralized in the ionomer resin/the number ofmoles of all carboxyl groups contained in the ionomer resin)×100

Examples of the metal ion used for neutralizing at least a part ofcarboxyl groups of (b-4) the ternary ionomer resin include: monovalentmetal ions such as sodium, potassium, lithium and the like; divalentmetals ions such as magnesium, calcium, zinc, barium, cadmium and thelike; trivalent metals ions such as aluminum and the like; and otherions such as tin, zirconium and the like.

Specific examples of (b-4) the ternary ionomer resin include “Himilan(registered trademark) (e.g. Himilan AM7327 (Zn), Himilan 1855 (Zn),Himilan 1856 (Na), Himilan AM7331 (Na) and the like)” commerciallyavailable from Du Pont-Mitsui Polychemicals Co., Ltd. Further, theternary ionomer resins commercially available from E.I. du Pont deNemours and Company include “Surlyn 6320 (Mg), Surlyn 8120 (Na), Surlyn8320 (Na), Surlyn 9320 (Zn), Surlyn 9320W (Zn) and the like”. Theternary ionomer resins commercially available from ExxonMobil ChemicalCorporation include “Iotek 7510 (Zn), lotek 7520 (Zn) and the like”. Itis noted that Na, Zn, Mg and the like described in the parentheses afterthe trade names indicate metal types of neutralizing metal ions. (b-4)The ternary ionomer resins may be used alone or as a mixture of at leasttwo of them.

(b-4) The ternary ionomer resin preferably has a flexural modulus of 10MPa or more, more preferably 11 MPa or more, even more preferably 12 MPaor more, and preferably has a flexural modulus of 100 MPa or less, morepreferably 97 MPa or less, even more preferably 95 MPa or less. If theflexural modulus of (b-4) the binary ionomer resin falls within theabove range, the flight performance of the resultant golf ball isexcellent because of the optimized spin rate on driver shots, and thedurability of the resultant golf ball becomes better.

(b-4) The ternary ionomer resin preferably has a melt flow rate (190°C., 2.16 kgf) of 0.1 g/10 min or more, more preferably 0.3 g/10 min ormore, even more preferably 0.5 g/10 min or more, and preferably has amelt flow rate (190° C., 2.16 kgf) of 20 g/10 min or less, morepreferably 15 g/10 min or less, even more preferably 10 g/10 min orless. If the melt flow rate (190° C., 2.16 kgf) of (b-4) the ternaryionomer resin is 0.1 g/10 min or more, the golf ball resin compositionhas better fluidity and thus it is possible to mold a thin constituentmember. If the melt flow rate (190° C., 2.16 kgf) of (b-4) the ternaryionomer resin is 20 g/10 min or less, the durability of the resultantgolf ball becomes better.

(b-4) The ternary ionomer resin preferably has a slab hardness of 20 ormore, more preferably 25 or more, even more preferably 30 or more, andpreferably has a slab hardness of 70 or less, more preferably 65 orless, even more preferably 60 or less in Shore D hardness. If theternary ionomer resin has a slab hardness of 20 or more in Shore Dhardness, the resultant constituent member does not become excessivelysoft and thus the golf ball has better resilience. If the ternaryionomer resin has a slab hardness of 70 or less in Shore D hardness, theresultant constituent member does not become excessively hard and thusthe golf ball has better durability.

In the golf ball resin composition of the present invention, the massratio of (A) component to (B) component ((A)/(B)) preferably ranges from15/85 to 80/20, more preferably ranges from 20/80 to 75/25, even morepreferably ranges from 25/75 to 70/30. If the mass ratio of (A)component to (B) component falls within the above range, the spin rateon driver shots is lowered because of the high flexural modulus, andrebound resilience becomes better, thus the flight distance on drivershots becomes great. Moreover, the durability of the resultant golf ballbecomes better.

Next, (C) the organically modified layered silicate used in the presentinvention will be explained. A layered silicate is a silicate having alayered structure. An organically modified layered silicate is the onethat is obtained by exchanging, with an organic onium ion, a part of orall the metal cations originally included between crystal layers in alayered silicate.

The layered silicate is not particularly limited as long as it is asilicate having a layered structure, and examples thereof include:layered silicates of kaolinites such as kaolinite, dickite, halloysite,chrysotile, lizardite, and amesite; layered silicates of smectites suchas montmorillonite, beidellite, nontronite, saponite, ferrous saponite,hectorite, sauconite, and stevensite; layered silicates of vermiculitessuch as dioctahedral vermiculite and trioctahedral vermiculite; layeredsilicates of micas such as white mica, paragonite, phlogopite, biotite,and lepidolite; layered silicates of brittle micas such as margarite,clintonite, and anandite; and layered silicates of chlorites such ascookeite, sudoite, clinochlore, chamosite, and nimite. These layeredsilicates may be natural or synthetic, and may be used solely or as amixture of two or more types. Among them, examples of the layeredsilicate preferably used in the present invention include: layeredsilicates of smectites such as montmorillonite, beidellite, nontronite,saponite, ferrous saponite, hectorite, sauconite, and stevensite;layered silicates of vermiculites such as dioctahedral vermiculite andtrioctahedral vermiculite; and layered silicates of micas such as whitemica, paragonite, phlogopite, biotite, and lepidolite. Montmorilloniteand layered silicates of micas are particularly suitable.

Each layer (primary particle) constituting the layered silicate ispreferably a nano size fine particle having a thickness of 10 nm orless, and preferably has a plate-like shape whose length and width areboth 1 μm or less. Although the size of the layered silicate is notparticularly limited, it is preferably 1 μm or less, more preferably 700nm or less, even more preferably 500 nm or less.

The cation exchange capacity of the layered silicate is preferably 30meq/100 g or more, more preferably 40 meq/100 g or more, even morepreferably 50 meq/100 g or more, and is preferably 200 meq/100 g orless, more preferably 180 meq/100 g or less, even more preferably 160meq/100 g or less. If the cation exchange capacity is 30 meq/100 g ormore, exchange with an organic onium ion can be performed sufficientlyduring organic modification and the interlayer distance can be expandedto a desired interval. If the cation exchange capacity is 200 meq/100 gor less, bonding strength between crystal layers does not becomeexcessively strong, thus the interlayer distance can be expanded easily.It should be noted that the cation exchange capacity is an amount ofexchangeable cations contained in per unit mass of the layered silicate.

The ion exchange ratio in the organically modified layered silicate ispreferably 50 mol % or more, more preferably 60 mol % or more, even morepreferably 70 mol % or more. If the ion exchange ratio in theorganically modified layered silicate is 50 mol % or more,dispersibility of the organically modified layered silicate in the resincomponent can be improved. Here, the ion exchange ratio in theorganically modified layered silicate is a ratio (percentage)indicating, among the exchangeable cations contained in the layeredsilicate prior to organic modification, how much the cations wereexchanged with organic cations.

The organic onium ion used for organically modifying the layeredsilicate is a cation having a carbon chain. The organic onium ion is notparticularly limited, and examples thereof include organic ammoniumions, organic phosphonium ions, and organic sulfonium ions.

As the organic ammonium ion, any one of primary ammonium ion, secondaryammonium ion, tertiary ammonium ion, and quaternary ammonium ion may beused.

Examples of the primary ammonium ion include decyl ammonium ion, dodecylammonium ion, octadecyl ammonium ion, oleyl ammonium ion, and benzylammonium ion.

Examples of the secondary ammonium ion include methyl dodecyl ammoniumion and methyl octadecyl ammonium ion.

Examples of the tertiary ammonium ion include dimethyl dodecyl ammoniumion and dimethyl octadecyl ammonium ion.

Examples of the quaternary ammonium ion include: benzyl trialkylammonium ions such as benzyl trimethyl ammonium ion, benzyl triethylammonium ion, benzyl tributyl ammonium ion, benzyl dimethyl dodecylammonium ion, and benzyl dimethyl octadecyl ammonium ion; alkyltrimethyl ammonium ions such as trioctyl methyl ammonium ion, trimethyloctyl ammonium ion, trimethyl dodecyl ammonium ion, and trimethyloctadecyl ammonium ion; and dimethyl dialkyl ammonium ions such asdimethyl dioctyl ammonium ion, dimethyl didodecyl ammonium ion, anddimethyl dioctadecyl ammonium ion.

Other than those described above, examples of the organic ammonium ionalso include ammonium ions such as aniline, p-phenylene diamine,α-naphthylamine, p-aminodimethyl aniline, benzidine, pyridine,piperidine, and 6-aminocaproic acid.

Among the ammonium ions described above, a quaternary ammonium ionhaving a total of 11 to 30 intramolecular carbon atoms is particularlysuitable from a standpoint of dispersibility of the layered silicate andformability of ionic bonds. Specific examples thereof include octadecylammonium ion, trioctyl methyl ammonium ion, trimethyl octadecyl ammoniumion, benzyl dimethyl dodecyl ammonium ion, and benzyl dimethyl octadecylammonium ion.

The organically modified layered silicate, whose exchangeable cationsexisting between layers were exchanged with an organic onium ion, of thepresent invention can be produced by causing a reaction between anorganic onium ion and a layered silicate having exchangeable metal ionsbetween layers thereof with a method known in the art. Specific examplesof such a method include a method of performing an ion exchange reactionin a polar solvent such as water, methanol, and ethanol; and a method ofcausing a direct reaction between a liquid or melted ammonium salt and alayered silicate.

The layered silicate may be pretreated with, in addition to the organiconium ion described above, a coupling agent such as an isocyanatecompound, an organic silane compound, an organic titanate compound, anorganoborane compound, and an epoxy compound.

The preferable coupling agent is the organic silane compound, andspecific examples thereof include epoxy group-containing alkoxysilanecompounds such as γ-glycidoxypropyl trimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β-(3,4-epoxycyclohexyl)ethyl trimethoxysilane;mercapto group-containing alkoxysilane compounds such asγ-mercaptopropyl trimethoxysilane and γ-mercaptopropyl triethoxysilane;ureido group-containing alkoxysilane compounds such as γ-ureidopropyltriethoxysilane, γ-ureidopropyl trimethoxysilane, andγ-(2-ureidoethyl)aminopropyl trimethoxysilane; isocyanatogroup-containing alkoxysilane compounds such as γ-isocyanatopropyltriethoxysilane, γ-isocyanatopropyl trimethoxysilane,γ-isocyanatopropylmethyl dimethoxysilane, γ-isocyanatopropylmethyldiethoxysilane, γ-isocyanatopropyl ethyl dimethoxysilane,γ-isocyanatopropyl ethyl diethoxysilane, and γ-isocyanatopropyltrichlorosilane; amino group-containing alkoxysilane compounds such asγ-(2-aminoethyl)aminopropylmethyl dimethoxysilane,γ-(2-aminoethyl)aminopropyl trimethoxysilane, and γ-aminopropyltrimethoxysilane; hydroxyl group-containing alkoxysilane compounds suchas γ-hydroxypropyl trimethoxysilane and γ-hydroxypropyl triethoxysilane;and carbon-carbon unsaturated group-containing alkoxysilane compoundssuch as γ-methacryloxypropyl trimethoxysilane, vinyl trimethoxysilane,and N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyl trimethoxysilanehydrochloride. In particular, the carbon-carbon unsaturatedgroup-containing alkoxysilane compound is used preferably.

Treatment of the layered silicate with the coupling agent may beperformed using any one of: a method of causing the coupling agent to beadsorbed by the layered silicate in a polar solvent such as water,methanol and ethanol, or in a mixed solvent thereof; a method ofdripping the coupling agent solution to the layered silicate which isbeing stirred in a high-speed agitation mixing machine such as aHenschel mixer to cause the coupling agent to be absorbed by the layeredsilicate; and a method of adding the silane coupling agent directly tothe layered silicate and mixing the mixture with a mortar or the like tocause the coupling agent to be absorbed by the layered silicate. In caseof treating the layered silicate with the coupling agent, water, acidicwater, alkaline water, or the like is preferably blended simultaneouslyin order to accelerate hydrolysis of alkoxy groups in the couplingagent. Furthermore, in order to enhance reaction efficiency of thecoupling agent, in addition to water, an organic solvent such asmethanol and ethanol that dissolves both water and the coupling agentmay be blended. The reaction may be further accelerated by heat-treatingsuch layered silicate which has been treated with the coupling agent. Inaddition, instead of treating the layered silicate with the couplingagent in advance, a so-called integral blending method of adding thecoupling agent when melting and kneading the layered silicate and thethermoplastic polyamide resin may be used.

Although the order of treating the layered silicate with the organiconium ion and treating the layered silicate with the coupling agent isnot particularly limited, it is preferred that the layered silicate istreated with the coupling agent after treated with the organic oniumion.

Specific examples of the organically modified layered silicate include:“Dellite (Registered trademark) 43B (refined montmorillonite, particlediameter: 500 nm, thickness: 1 nm, quaternary ammonium salt treated:quaternary ammonium salt having a benzyl group, a tallowate group andtwo methyl groups)” and “Dellite (Registered trademark) 67G (refinedmontmorillonite, particle diameter: 500 nm, thickness: 1 nm, quaternaryammonium salt treated: quaternary ammonium salt having two tallowategroups and two methyl groups)” commercially available from LaviosaChimica Mineraria S.p.A.; and “S-Ben” manufactured by HOJUN Co., Ltd.

The content of (C) the organically modified layered silicate in the golfball resin composition of the present invention is preferably 0.1 partsby mass or more, more preferably 0.12 parts by mass or more, even morepreferably 0.15 parts by mass or more, and is preferably 50 parts bymass or less, more preferably 30 parts by mass or less, even morepreferably 20 parts by mass or less, with respect to 100 parts by massof a total of (A) component and (B) component. If the content of theorganically modified layered silicate falls within the above range, thephysical property improving effect obtained by the addition becomesbetter, and decrease in toughness can be suppressed. By containing (C)the organically modified layered silicate in the golf ball resincomposition, the flexural modulus improves and spin rate on driver shotsdecreases, thus flight distance on driver shots can be increased.

The golf ball resin composition of the present invention may furthercontain (D) an organic onium salt as necessary. (D) The organic oniumsalt is a compound group represented by ammonium salts, phosphoniumsalts, and sulfonium salts. Among them, the ammonium salt and thephosphonium salt are preferably used, in particular, the ammonium saltis preferably used. As the ammonium salt, any one of chloride, bromide,acetate, and sulfate of a primary ammonium, a secondary ammonium, atertiary ammonium and a quaternary ammonium may be used.

Examples of the primary ammonium salt include salts of decyl ammonium,dodecyl ammonium, octadecyl ammonium, oleyl ammonium, and benzylammonium.

Examples of the secondary ammonium salt include salts of methyl dodecylammonium and methyl octadecyl ammonium.

Examples of the tertiary ammonium salt include salts of dimethyl dodecylammonium and dimethyl octadecyl ammonium.

Examples of the quaternary ammonium salt include: benzyl trialkylammonium salts of benzyl trimethyl ammonium, benzyl triethyl ammonium,benzyl tributyl ammonium, benzyl dimethyl dodecyl ammonium, and benzyldimethyl octadecyl ammonium; alkyl trimethyl ammonium salts of trioctylmethyl ammonium, trimethyl octyl ammonium, trimethyl dodecyl ammonium,and trimethyl octadecyl ammonium; and dimethyl dialkyl ammonium salts ofdimethyl dioctyl ammonium, dimethyl didodecyl ammonium, and dimethyldioctadecyl ammonium.

In addition to those described above, examples of the ammonium salt alsoinclude ammonium salts of aniline, p-phenylene diamine, α-naphthylamine,p-aminodimethyl aniline, benzidine, pyridine, piperidine, 6-aminocaproicacid, 11-aminoundecanoic acid, and 12-aminododecanoic acid.

Among the ammonium salts described above, trioctyl methyl ammoniumchloride, trimethyl octadecyl ammonium chloride, benzyl dimethyl dodecylammonium chloride, and benzyl dimethyl octadecyl ammonium chloride maybe suitably used.

The organic onium ion used for organically modifying the layeredsilicate and the organic onium ion forming the organic onium salt whichis used as (D) component may be the same or may be different. In thecase where the same organic onium ion is used, the organic onium saltmay be added in an excessive amount when producing the organicallymodified layered silicate which is (C) component, to keep the organiconium salt remain in (C) component.

From a standpoint of physical properties of the resultant resincomposition and gas generation, the blended amount of the organicammonium salt when the organic ammonium salt is blended as (D) theorganic onium salt is preferably in a range of 0.01 part by mass to 10parts by mass, more preferably in a range of 0.05 part by mass to 5parts by mass, and particularly preferably in a range of 0.1 part bymass to 3 parts by mass, with respect to 100 parts by mass of (A) thepolyamide resin.

The golf ball resin composition of the present invention may furthercontain a fluidity modifier. Examples of the fluidity modifier includefatty acids and/or metal salts thereof.

The fatty acid is not particularly limited, and examples thereofinclude: saturated fatty acids such as butyric acid, valeric acid,hexanoic acid, heptanoic acid, octanoic acid, pelargonic acid, decanoicacid, lauric acid, myristic acid, palmitic acid, heptadecanoic acid,stearic acid, icosanoic acid, behenic acid, lignoceric acid, and ceroticacid; and unsaturated fatty acids such as palmitoleic acid, oleic acid,linolic acid, α-linolenic acid, γ-linolenic acid, and arachidonic acid.

The fatty acid metal salt is not particularly limited, and examplesthereof include metal salts of the aforementioned fatty acids. Examplesof the fatty acid metal salt include: monovalent metal salts such asfatty acid sodium salts, fatty acid potassium salts, and fatty acidlithium salts; divalent metal salts such as fatty acid magnesium salts,fatty acid calcium salts, fatty acid zinc salts, fatty acid bariumsalts, and fatty acid cadmium salts; and trivalent metal salts such asfatty acid aluminum salts. Among them, as the fatty acid metal salt,divalent metal salts of saturated fatty acids such as magnesiumstearate, calcium stearate, zinc stearate, barium stearate, and copperstearate are preferable.

The blended amount of the fluidity modifier is preferably 0.5 part bymass or more, more preferably 1.5 parts by mass or more, and ispreferably 30 parts by mass or less, more preferably 25 parts by mass orless, with respect to 100 parts by mass of a total of (A) component and(B) component. If the blended amount of the fluidity modifier fallswithin the above range, the fluidity of the golf ball resin compositionimproves. As a result, molding a thin constituting member becomespossible.

The golf ball resin composition of the present invention may furthercontain a pigment component such as a white pigment (for example,titanium oxide) and a blue pigment, a weight adjusting agent, adispersant, an antioxidant, an ultraviolet absorber, a light stabilizer,a fluorescent material, a fluorescent brightener, and the like, as longas they do not impair the performance of the golf ball.

The golf ball resin composition of the present invention can beobtained, for example, by dry blending (A) component, (B) component, and(C) component. Further, the dry blended mixture may be extruded into apellet form. The dry blending is preferably carried out by using forexample, a mixer capable of blending raw materials in a pellet form, andis more preferably carried out by using a tumbler type mixer. Extrudingcan be carried out by using publicly known extruders such as asingle-screw extruder, a twin-screw extruder, a twin-single screwextruder, and the like.

The golf ball resin composition of the present invention preferably hasa melt flow rate (240° C., 2.16 kgf) of 5 g/10 min or more, morepreferably 8 g/10 min or more, even more preferably 10 g/10 min or more,and preferably has a melt flow rate (240° C., 2.16 kgf) of 100 g/10 minor less, more preferably 70 g/10 min or less, even more preferably 40g/10 min or less. If the golf ball resin composition has a melt flowrate in the above range, the moldability is good.

The golf ball resin composition of the present invention preferably hasa slab hardness of 65 or more, more preferably 67 or more, even morepreferably 69 or more in shore D hardness, and the golf ball resincomposition preferably has a slab hardness of 80 or less, morepreferably 78 or less, even more preferably 76 or less in shore Dhardness. By using the golf ball resin composition having a slabhardness of 65 or more in shore D hardness, the spherical bodyconsisting of the core and the intermediate layer has an outer-hardinner-soft structure, thus the golf ball showing a higher launch angleand low spin rate on driver shots can be obtained. As a result, theflight distance of the golf ball on driver shots becomes larger. On theother hand, by using the golf ball resin composition having a slabhardness of 80 or less in shore D hardness, the golf ball excellent inthe durability can be provided. Here, the slab hardness of the golf ballresin composition is a hardness of the golf ball resin composition thatis molded into a sheet form, and is measured by the method describedlater.

The golf ball resin composition of the present invention preferably hasa flexural modulus of 400 MPa or more, more preferably 430 MPa or more,even more preferably 450 MPa or more, and preferably has a flexuralmodulus of 4,000 MPa or less, more preferably 3,500 MPa or less, evenmore preferably 3,000 MPa or less. If the flexural modulus of the golfball resin composition is 400 MPa or more, the obtained golf ball has anouter-hard inner-soft structure and thus the flight distance becomelarger. On the other hand, if the flexural modulus of the golf ballresin composition is 4,000 MPa or less, the obtained golf ball becomesappropriately soft and thus the shot feeling becomes better.

The golf ball resin composition of the present invention preferably hasa rebound resilience (%) of 48 or more, more preferably 49 or more, evenmore preferably 50 or more. If the rebound resilience (%) of the golfball resin composition is 48 or more, the obtained golf ball has ahigher resilience and thus the flight distance becomes larger.

The melt flow rate, flexural modulus, rebound resilience and slabhardness of the golf ball resin composition can be adjusted by choosingappropriately the kinds, contents, or the like of (A) component, (B)component and (C) component.

(2) Golf Ball

The golf ball of the present invention comprises a core, at least oneintermediate layer covering the core, and a cover covering theintermediate layer, wherein at least one of the core, at least oneintermediate layer or cover is formed from the golf ball resincomposition of the present invention. In one preferable embodiment, thegolf ball comprises a core, at least one intermediate layer covering thecore, and a cover covering the intermediate layer, wherein at least oneintermediate layer is formed from the golf ball resin composition of thepresent invention.

In the following, the golf ball of the present invention will beexplained based on the preferable embodiment that comprises a core, atleast one intermediate layer covering the core, and a cover covering theintermediate layer (including a three-piece golf ball), wherein at leastone intermediate layer is formed from the golf ball resin composition ofthe present invention.

Core Material

The core generally has a spherical shape, but may be an irregular coreprovided with a rib on the surface thereof so that the surface of thespherical core is divided by the ribs. A rubber composition(hereinafter, sometimes simply referred to as “core rubber composition”)may be employed for the core. The core can be molded by, for example,heat-pressing a rubber composition containing a base rubber, acrosslinking initiator, a co-crosslinking agent, and a filler.

As the base rubber, a natural rubber and/or a synthetic rubber may beused. Examples of the base rubber are a polybutadiene rubber, a naturalrubber, a polyisoprene rubber, a styrene polybutadiene rubber, and anethylene-propylene-diene rubber (EPDM). Among them, particularlypreferred is the high cis-polybutadiene having cis-bond in a proportionof 40 mass % or more, more preferably 70 mass % or more, even morepreferably 90 mass % or more in view of its superior resilience.

The crosslinking initiator is blended to crosslink the base rubbercomponent. As the crosslinking initiator, an organic peroxide ispreferably used. Examples of the organic peroxide are dicumyl peroxide,1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane,2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and di-t-butyl peroxide. Amongthem, dicumyl peroxide is preferable. The amount of the crosslinkinginitiator to be blended in the rubber composition is preferably 0.3 partby mass or more, more preferably 0.4 part by mass or more, and ispreferably 5 parts by mass or less, more preferably 3 parts by mass orless with respect to 100 parts by mass of the base rubber. If the amountis less than 0.3 part by mass, the core becomes too soft, and theresilience tends to be lowered, and if the amount is more than 5 partsby mass, the amount of the co-crosslinking agent must be lowered inorder to obtain an appropriate hardness, which tends to cause theinsufficient resilience.

The co-crosslinking agent is not particularly limited so long as it hasan action of crosslinking a rubber molecule by graft polymerization to abase rubber molecular chain, for example, an α,β-unsaturated carboxylicacid having 3 to 8 carbon atoms or a metal salt thereof can be used, thepreferable examples include acrylic acid, methacrylic acid or a metalsalt thereof. As the metal constituting the metal salt, for example,zinc, magnesium, calcium, aluminum and sodium may be used, and amongthem, zinc is preferred because it provides high resilience.

The amount of the co-crosslinking agent to be used is preferably 10parts by mass or more, more preferably 15 parts by mass or more, evenmore preferably 20 parts by mass or more, and is preferably 55 parts bymass or less, more preferably 50 parts by mass or less, even morepreferably 48 parts by mass or less, with respect to 100 parts by massof the base rubber. If the amount of the co-crosslinking agent to beused is less than 10 parts by mass, the amount of the crosslinkinginitiator must be increased to obtain an appropriate hardness, whichtends to lower the resilience. On the other hand, if the amount of theco-crosslinking agent to be used is more than 55 parts by mass, the corebecomes so hard that the shot feeling may be lowered.

The filler contained in the core rubber composition is mainly blended asa weight adjusting agent in order to adjust the weight of the golf ballobtained as the final product, and may be blended as necessary. Examplesof the filler include an inorganic filler such as zinc oxide, bariumsulfate, calcium carbonate, magnesium oxide, tungsten powder, andmolybdenum powder. The amount of the filler to be blended in the rubbercomposition is preferably 0.5 part by mass or more, more preferably 1part by mass or more, and is preferably 30 parts by mass or less, morepreferably 20 parts by mass or less, with respect to 100 parts by massof the base rubber. If the amount of the filler to be blended is lessthan 0.5 part by mass, it becomes difficult to adjust the weight, whileif it is more than 30 parts by mass, the weight ratio of the rubbercomponent becomes small and the resilience tends to be lowered.

In the core rubber composition, an organic sulfur compound, anantioxidant or a peptizing agent may be blended appropriately inaddition to the base rubber, the crosslinking initiator, theco-crosslinking agent and the filler.

Examples of the organic sulfur compound include thiophenols,thionaphthols, polysulfides, thiocarboxylic acids, dthiocarboxylicacids, sulfenamindes, thiurams, dithiocarbamates, thiazoles, and thelike.

Among them, diphenyl disulfides may be preferably used as the organicsulfur compound. Examples of the diphenyl disulfides include diphenyldisulfide; mono-substituted diphenyl disulfides such asbis(4-chlorophenyl)disulfide, bis(3-chlorophenyl)disulfide,bis(4-bromophenyl)disulfide, bis(3-bromophenyl)disulfide,bis(4-fluorophenyl)disulfide, bis(4-iodophenyl)disulfide andbis(4-cyanophenyl)disulfide; di-substituted diphenyl disulfides such asbis(2,5-dichlorophenyl)disulfide, bis(3,5-dichlorophenyl)disulfide,bis(2,6-dichlorophenyl)disulfide, bis(2,5-dibromophenyl)disulfide,bis(3,5-dibromophenyl)disulfide, bis(2-chloro-5-bromophenyl)disulfide,and bis(2-cyano-5-bromophenyl)disulfide; tri-substituted diphenyldisulfides such as bis(2,4,6-trichlorophenyl)disulfide, andbis(2-cyano-4-chloro-6-bromophenyl)disulfide; tetra-substituted diphenyldisulfides such as bis(2,3,5,6-tetra chlorophenyl)disulfide;penta-substituted diphenyl disulfides such asbis(2,3,4,5,6-pentachlorophenyl)disulfide andbis(2,3,4,5,6-pentabromophenyl)disulfide. These diphenyl disulfides canenhance resilience by having some influence on the state ofvulcanization of vulcanized rubber. Among them, diphenyl disulfide orbis(pentabromophenyl) disulfide is preferably used since the golf ballhaving particularly high resilience can be obtained. The amount of theorganic sulfur compound to be blended is preferably 0.1 part by mass ormore, more preferably 0.3 part by mass or more, and is preferably 5.0parts by mass or less, more preferably 3.0 parts by mass or less withrespect to 100 parts by mass of the base rubber.

The amount of the antioxidant to be blended is preferably 0.1 part bymass or more and is preferably 1 part by mass or less with respect to100 parts by mass of the base rubber. Further, the amount of thepeptizing agent to be blended is preferably 0.1 part by mass or more andis preferably 5 parts by mass or less with respect to 100 parts of thebase rubber.

Cover Material

The cover of the golf ball of the present invention is preferably formedfrom a cover composition containing a resin component. The examples ofthe resin component include: an ionomer resin such as “Himilan”commercially available from Du Pont-Mitsui Polychemicals Co., Ltd.,“Surlyn” commercially available from E.I. du Pont de Nemours andCompany, and “Iotek” commercially available from ExxonMobil ChemicalCorporation; a thermoplastic polyurethane elastomer having a trade nameof “Elastollan (registered trademark) (e.g. Elastollan XNY85A,Elastollan XNY97A)” commercially available from BASF Japan Ltd.; athermoplastic polyamide elastomer having a trade name of “Pebax(registered trademark) (e.g. Pebax 2533)” commercially available fromArkema K. K.; a thermoplastic polyester elastomer having a trade name of“Hytrel (registered trademark) (e.g. Hytrel 3548, Hytrel 4047)”commercially available from Du Pont-Toray Co., Ltd.; and a thermoplasticstyrene elastomer having a trade name of “Rabalon (registeredtrademark)” commercially available from Mitsubishi Chemical Corporation.In addition, (B) component, namely, (b-1) the binary copolymer composedof an olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbonatoms, or (b-3) the ternary copolymer composed of an olefin, anα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and anα,β-unsaturated carboxylic acid ester may be used. These resincomponents may be used solely or as a mixture of at least two of them.

The cover composition preferably contains the thermoplastic polyurethaneelastomer or the ionomer resin, as the resin component. The content ofthe thermoplastic polyurethane elastomer or the ionomer resin in theresin component of the cover composition is preferably 50 mass % ormore, more preferably 60 mass % or more, even more preferably 70 mass %or more. In one preferable embodiment, the cover composition containsthe thermoplastic polyurethane elastomer. By using the polyurethanecover, controllability on approach shots can be improved.

In addition to the aforementioned resin component, the cover compositionmay further contain a pigment component such as a white pigment (forexample, titanium oxide), a blue pigment, a red pigment, or the like; aweight adjusting agent such as zinc oxide, calcium carbonate, bariumsulfate, or the like; a dispersant; an antioxidant; an ultravioletabsorber; a light stabilizer; a fluorescent material; a fluorescentbrightener; or the like, as long as they do not impair the performanceof the cover.

The amount of the white pigment (for example, titanium oxide), withrespect to 100 parts by mass of the resin component constituting thecover, is preferably 0.5 part by mass or more, more preferably 1 part bymass or more, and is preferably 10 parts by mass or less, morepreferably 8 parts by mass or less. If the amount of the white pigmentis 0.5 part by mass or more, it is possible to impart the opacity to thecover. If the amount of the white pigment is more than 10 parts by mass,the durability of the resultant cover may deteriorate.

The cover composition preferably has a slab hardness of 65 or less, morepreferably 60 or less, even more preferably 55 or less in Shore Dhardness. If the cover composition has a slab hardness of 65 or less,the spin rate on approach shots with short irons increases. As a result,the golf ball having a good controllability on approach shots isobtained. In order to ensure the spin rate sufficiently for approachshots, the cover composition preferably has a slab hardness of 20 ormore, more preferably 25 or more, even more preferably 30 or more inShore D hardness.

Manufacturing Method for Golf Ball

The core of the golf ball of the present invention can be obtained bymixing, kneading the above mentioned core rubber composition and moldingthe core rubber composition in a mold. The conditions for molding thecore rubber composition are not particularly limited, but molding isgenerally carried out for 10 to 60 minutes at a temperature of 130° C.to 200° C. under a pressure from 2.9 MPa to 11.8 MPa. Particularly,molding the core rubber composition is preferably carried out for 10 to60 minutes at a temperature of 130° C. to 200° C., or alternatively in atwo-step heating for 20 to 40 minutes at a temperature of 130° C. to150° C. and continuously for 5 to 15 minutes at a temperature of 160° C.to 180° C.

The intermediate layer is formed, for example, by covering the core withthe golf ball resin composition. The method to form the intermediatelayer is not particularly limited, and includes, for example, anembodiment which comprises molding the golf ball resin composition intoa semi-spherical half shell, covering the core with the two half shells,and subjecting the core with the two half shells to compression moldingat a temperature of 130° C. to 170° C. for 1 to 5 minutes; and anembodiment which comprises injection molding the golf ball resincomposition directly onto the core to cover the core. The intermediatelayer of the golf ball of the present invention is preferably formed byinjection molding. The intermediate layer can be produced more easily byinjection molding.

In the case of injection molding the golf ball resin composition ontothe core to form the intermediate layer, the golf ball resin compositionextruded in a pellet form may be used for injection molding, or variousmaterials such as the resin components and the pigment may be dryblended, followed by directly injection molding the blended material. Inthe present invention, the golf ball resin composition extruded in apellet form is preferably used for injection molding. It is preferred touse upper and lower molds having a semi-spherical cavity and pimples forforming the intermediate layer, wherein a part of the pimple also servesas a retractable hold pin. When forming the intermediate layer byinjection molding, the hold pin is protruded to hold the core, the golfball resin composition which has been heated and melted is charged andthen cooled to obtain the intermediate layer.

When molding the intermediate layer in a compression molding method,molding of the half shell can be performed by either the compressionmolding method or the injection molding method, and the compressionmolding method is preferred. Compression molding the golf ball resincomposition into the half shell can be carried out, for example, under apressure of 1 MPa or more and 20 MPa or less at a temperature of −20° C.or more and +70° C. or less relative to the flow beginning temperatureof the golf ball resin composition. By performing the molding under theabove conditions, the half shell having a uniform thickness can beformed. Examples of the method for molding the intermediate layer byusing the half shell include, for example, a method which comprisescovering the core with two half shells and then performing compressionmolding. Compression molding half shells into the intermediate layer canbe carried out, for example, under a pressure of 0.5 MPa or more and 25MPa or less at a temperature of −20° C. or more and +70° C. or lessrelative to the flow beginning temperature of the golf ball resincomposition. By performing the molding under the above conditions, theintermediate layer having a uniform thickness can be formed.

The molding temperature means the highest temperature where atemperature at the surface of the concave portion of the lower moldreaches from closing through opening the molds. Further, the flowbeginning temperature of the golf ball resin composition can be measuredin a pellet form under the following conditions by using “Flow TesterCFT-500” manufactured by Shimadzu Corporation.

Measuring conditions: Area size of a plunger: 1 cm², Die length: 1 mm,Die diameter: 1 mm, Load: 588.399 N, Start temperature: 30° C., andTemperature increase rate: 3° C./min.

The method for molding the cover of the golf ball of the presentinvention includes, for example, an embodiment which comprises moldingthe cover composition into a hollow shell, covering the spherical bodyconsisting of the core and the intermediate layer with a plurality ofhollow shells and subjecting to compression molding (preferably anembodiment which comprises molding the cover composition into a hollowhalf shell, covering the spherical body consisting of the core and theintermediate layer with two half shells and subjecting to compressionmolding); or an embodiment which comprises injection molding the covercomposition directly onto the spherical body consisting of the core andthe intermediate layer.

When molding the cover in a compression molding method, molding of thehalf shell can be performed by either the compression molding method orthe injection molding method, and the compression molding method ispreferred. Compression molding the cover composition into a half shellcan be carried out, for example, under a pressure of 1 MPa or more and20 MPa or less at a temperature of −20° C. or more and 70° C. or lessrelative to the flow beginning temperature of the cover composition. Byperforming the molding under the above conditions, the half shell havinga uniform thickness can be formed. Examples of the method for moldingthe cover by using the half shell include a method which comprisescovering the spherical body consisting of the core and the intermediatelayer with two half shells and then performing compression molding.Compression molding half shells into the cover can be carried out, forexample, under a pressure of 0.5 MPa or more and 25 MPa or less at atemperature of −20° C. or more and 70° C. or less relative to the flowbeginning temperature of the cover composition. By performing themolding under the above conditions, the golf ball cover having a uniformthickness can be formed.

In the case of injection molding the cover composition into the cover,the cover composition extruded in a pellet form may be used forinjection molding, or the cover materials such as the base resincomponents and the pigment may be dry blended, followed by directlyinjection molding the blended material. It is preferred to use upper andlower molds having a semi-spherical cavity and pimples for forming thecover, wherein a part of the pimples also serves as a retractable holdpin. When molding the cover by injection molding, the hold pin isprotruded to hold the spherical body consisting of the core and theintermediate layer, the cover composition is charged and then cooled toobtain the cover. For example, the cover composition heated at atemperature ranging from 200° C. to 250° C. is charged into a mold heldunder a pressure of 9 MPa to 15 MPa for 0.5 to 5 seconds, and aftercooling for 10 to 60 seconds, the mold is opened to obtain the cover.

The concave portions called “dimple” are usually formed on the surfaceof the cover. The total number of dimples formed on the cover ispreferably 200 or more and 500 or less. If the total number is less than200, the dimple effect is hardly obtained. On the other hand, if thetotal number exceeds 500, the dimple effect is hardly obtained becausethe size of the respective dimples is small. The shape (shape in a planview) of dimples formed on the cover includes, for example, withoutlimitation, a circle; a polygonal shape such as roughly triangularshape, roughly quadrangular shape, roughly pentagonal shape or roughlyhexagonal shape; or another irregular shape. The shape of dimples isemployed solely or at least two of them may be used in combination.

After the cover is molded, the golf ball body is ejected from the mold,and as necessary, the golf ball body is preferably subjected to surfacetreatments such as deburring, cleaning, and sandblast. If desired, apaint film or a mark may be formed. The paint film preferably has athickness of, but not limited to, 5 μm or more, more preferably 7 μm ormore, and preferably has a thickness of 50 μm or less, more preferably25 μm or less, even more preferably 18 μm or less. If the thickness isless than 5 μm, the paint film is easy to wear off due to continued useof the golf ball, and if the thickness is more than 50 μm, the dimpleeffect is reduced, resulting in lowering flight performance of the golfball.

Structure of Golf Ball

The core of the golf ball of the present invention preferably has adiameter of 34.8 mm or more, more preferably 35.0 mm or more, even morepreferably 35.2 mm or more, and preferably has a diameter of 41.2 mm orless, more preferably 41.0 mm or less, even more preferably 40.8 mm orless. If the core has a diameter of 34.8 mm or more, the thickness ofthe intermediate layer or the cover does not become too thick and thusthe resilience becomes better. On the other hand, if the core has adiameter of 41.2 mm or less, the thickness of the intermediate layer orthe cover does not become too thin, and thus the intermediate layer orthe cover functions better.

When the core has a diameter from 34.8 mm to 41.2 mm, the compressiondeformation amount (shrinking amount of the core along the compressiondirection) of the core when applying a load from 98 N as an initial loadto 1275 N as a final load on the core is preferably 1.90 mm or more,more preferably 2.00 mm or more, even more preferably 2.10 mm or more,and is preferably 4.00 mm or less, more preferably 3.90 mm or less, evenmore preferably 3.80 mm or less. If the compression deformation amountis 1.90 mm or more, the shot feeling of the golf ball becomes better. Ifthe compression deformation amount is 4.00 mm or less, the resilience ofthe golf ball becomes better.

The core preferably has a surface hardness of 45 or more, morepreferably 50 or more, even more preferably 55 or more, and preferablyhas a surface hardness of 65 or less, more preferably 62 or less, evenmore preferably 60 or less in Shore D hardness. If the surface hardnessof the core is 45 or more in Shore D hardness, the core does not becomeexcessively soft, and thus the better resilience is obtained. Further,if the surface hardness of the core is 65 or less in Shore D hardness,the core does not become excessively hard, and thus the better shotfeeling is obtained.

The core preferably has a center hardness of 30 or more, more preferably32 or more, even more preferably 35 or more in Shore D hardness. If thecenter hardness of the core is less than 30 in Shore D hardness, thecore becomes so soft that the resilience may be lowered. Further, thecore preferably has a center hardness of 50 or less, more preferably 48or less, even more preferably 46 or less in Shore D hardness. If thecenter hardness exceeds 50 in Shore D hardness, the core becomes so hardthat the shot feeling tends to be lowered. In the present invention, thecenter hardness is a hardness measured with a Shore D type springhardness tester at the central point of the cut plane which is obtainedby cutting the core into two hemispheres.

Further, the surface hardness of the core is preferably larger than thecenter hardness of the core. If the surface hardness of the core islarger than the center hardness of the core, the golf ball showing highlaunch angle and low spin rate on driver shots can be obtained. The golfball showing high launch angle and low spin rate travels a great flightdistance. The core preferably has a hardness difference (surfacehardness—center hardness) between the surface hardness and the centerhardness thereof of 4 or more, more preferably 7 or more in Shore Dhardness. The hardness difference (surface hardness—center hardness) ispreferably 40 or less, more preferably 35 or less in Shore D hardness.If the hardness difference is excessively large, the durability of thegolf ball may be lowered.

The intermediate layer of the golf ball of the present inventionpreferably has a thickness of 1.5 mm or less, more preferably 1.4 mm orless, even more preferably 1.2 mm or less. If the thickness of theintermediate layer is 1.5 mm or less, the resilience and shot feeling ofthe obtained golf ball become better. The thickness of the intermediatelayer is preferably 0.5 mm or more, more preferably 0.6 mm or more, evenmore preferably 0.7 mm or more. If the thickness of the intermediatelayer is 0.5 mm or more, it becomes easy to mold the intermediate layer,and the durability of the obtained golf ball improves.

In the case that the golf ball of the present invention comprises atleast two intermediate layers, at least one intermediate layer may beformed from the above mentioned golf ball resin composition. In thiscase, the outermost intermediate layer is preferably formed from theabove mentioned golf ball resin composition. In addition, in onepreferable embodiment, all the intermediate layers are formed from theabove mentioned golf ball resin composition.

The thickness of the cover is preferably 2.0 mm or less, more preferably1.6 mm or less, even more preferably 1.2 mm or less, most preferably 1.0mm or less. If the thickness of the cover is 2.0 mm or less, theresilience and shot feeling of the obtained golf ball become better. Thethickness of the cover is preferably 0.1 mm or more, more preferably 0.2mm or more, even more preferably 0.3 mm or more. If the thickness of thecover is less than 0.1 mm, it may become difficult to mold the cover. Inaddition, the durability and the wear resistance of the cover maydeteriorate.

When the golf ball of the present invention has a diameter from 40 mm to45 mm, the compression deformation amount (shrinking amount of the golfball along the compression direction) of the golf ball when applying aload from 98 N as an initial load to 1275 N as a final load on the golfball is preferably 2.0 mm or more, more preferably 2.2 mm or more, andis preferably 4.0 mm or less, more preferably 3.5 mm or less. The golfball having a compression deformation amount of 2.0 mm or more is notexcessively hard and thus has good shot feeling. If the compressiondeformation amount is 4.0 mm or less, the resilience of the golf ballbecomes better.

EXAMPLES

Hereinafter, the present invention will be described in detail by way ofexamples. The present invention is not limited to the examples describedbelow. Various changes and modifications can be made without departingfrom the spirit and scope of the present invention.

(1) Melt Flow Rate (MFR) (g/10 min)

MFR was measured according to JIS K7210 by using a flow tester (SHIMADZUFlow Tester CFT-100C, manufactured by SHIMADZU CORPORATION). Measurementwas carried out at the conditions of: 190° C.×2.16 kgf; 210° C.×2.16kgf; 230° C.×2.16 kgf; 240° C.×2.16 kgf; or 260° C.×load 325 gf.

(2) Flexural Modulus (Three-Point Bending, MPa)

A test piece with a length of 80.0±2 mm, a width of 10.0±0.2 mm and athickness of 4.0±0.2 mm was produced by injection molding the golf ballresin composition. The obtained test piece was stored at 23° C.±2° C.for 24 hours or more in a moisture-proof container immediately. Afterthe test piece was taken out of the moisture-proof container, theflexural modulus thereof was measured rapidly (within fifteen minutes)according to ISO 178. The measurement was carried out at the temperatureof 23° C., the humidity of 50 RH %.

(3) Slab Hardness (Shore D Hardness)

Sheets with a thickness of about 2 mm were produced by injection moldingthe cover composition or the golf ball resin composition, and stored at23° C. for two weeks. Three or more of these sheets were stacked on oneanother so as not to be affected by the measuring substrate on which thesheets were placed, and the hardness of the stack was measured with atype P1 auto loading durometer manufactured by Kobunshi Keiki Co., Ltd.,provided with a Shore D type spring hardness tester.

(4) Core Hardness (Shore D Hardness)

The Shore D hardness measured at the surface of the core by using a typeP1 auto loading durometer manufactured by Kobunshi Keiki Co., Ltd.,provided with a Shore D type spring hardness tester prescribed inASTM-D2240 was adopted as the surface hardness Hs of the core. The ShoreD hardness measured at the central point of the cut plane which isobtained by cutting the core into two hemispheres was adopted as thecenter hardness Ho of the core.

(5) Compression Deformation Amount (mm)

The compression deformation amount of the golf ball or core (shrinkingamount of the golf ball or core along the compression direction), whenapplying a load from 98 N as an initial load to 1275 N as a final loadto the golf ball or core, was measured.

(6) Rebound Resilience (%)

A sheet with a thickness of about 2 mm was produced by heatpress-molding the golf ball resin composition. A circle-shaped testpiece having a diameter of 28 mm was cut out of this sheet, and 6 piecesof the test piece were stacked to prepare a cylindrical test piecehaving a thickness of about 12 mm and a diameter of 28 mm. Thecylindrical test piece was subjected to the Lupke type reboundresilience test (testing temperature 23° C., humidity 50 RH %).Preparation of the test piece and the testing method are based on JISK6255.

(7) Coefficient of Restitution

A 198.4 g of metal cylindrical object was forced to collide with eachgolf ball at a speed of 45 m/sec, and the speeds of the cylindricalobject and the golf ball before and after the collision were measured.Based on these speeds and the mass of each object, the coefficient ofrestitution for each golf ball was calculated. The measurement wasconducted by using twelve samples for each golf ball, and the averagevalue was regarded as the coefficient of restitution for the golf ball.

(8) Flight Distance (m), Ball Initial Speed (m/s) and Spin Rate (rpm) onDriver Shots

A metal-headed W#1 driver (MO, Shaft: S, loft: 10.5°, manufactured byDunlop Sports Limited) was installed on a swing robot M/C manufacturedby Golf Laboratories, Inc. A golf ball was hit at a head speed of 50m/sec, and the ball initial speed, spin rate and flight distance (thedistance from the launch point to the stop point) right after hittingthe golf ball were measured. This measurement was conducted twelve timesfor each golf ball, and the average value thereof was adopted as themeasurement value for the golf ball. A sequence of photographs of thehit golf ball were taken for measuring the spin rate right after hittingthe golf ball.

[Preparation of Organically Modified Layered Silicate]

100 g of Na-type montmorillonite (Kunimine Industries Co., Ltd., KunipiaF, cation exchange capacity: 120 meq/100 g) was stirred and dispersed in10 L of warm water, and 2 L of warm water, in which 51 g (equivalent tocation exchange capacity) of benzyl dimethyl octadecyl ammonium chloridewas dissolved, was added therein, the resultant mixture was stirred for1 hour. The generated precipitate was filtered for separation, andrinsed with warm water. This operation of rinsing and filtering forseparation was performed for three times. The obtained solid wasvacuum-dried at 80° C. to obtain a dried organically modified layeredsilicate. Soxhlet extraction was performed for 5 hours with methanol.When the amount of benzyl dimethyl octadecyl ammonium chloride containedin the organically modified layered silicate was quantified, it wasrevealed that the amount was 0.1 mass % or less of the amount of theorganically modified layered silicate.

[Production of Golf Ball]

(1) Production of Core

The rubber compositions having formulations shown in Table 1 werekneaded, and heat-pressed in upper and lower molds, each having ahemispherical cavity, at 170° C. for 30 minutes to prepare the core.

TABLE 1 Core composition Formulation (Parts by mass) Polybutadienerubber 100 Zinc acrylate 39 Zinc oxide 5 Barium sulfate Appropriateamount* Diphenyl disulfide 0.5 Dicumyl peroxide 0.8 Diameter (mm) 39.7Surface hardness (Shore D) 58 Center hardness (Shore D) 41 Compressiondeformation amount (mm) 2.7 *Depending on the core composition,adjustment was made such that the golf ball had a mass of 45.3 g.

-   Polybutadiene rubber: “BR-730 (high-cis polybutadiene)” manufactured    by JSR Corporation.-   Zinc acrylate: “ZNDA-90S” manufactured by Nihon Jyoryu Kogyo Co.,    Ltd.-   Zinc oxide: “Ginrei R” manufactured by Toho Zinc Co., Ltd.-   Barium sulfate: “Barium Sulfate BD” manufactured by Sakai Chemical    Industry Co., Ltd.-   Dicumyl peroxide: “Percumyl (registered trademark) D” manufactured    by NOF Corporation.-   Diphenyl disulfide: manufactured by Sumitomo Seika Chemicals Co.,    Ltd.    (2) Production of Intermediate Layer

Next, the blending materials shown in Tables 2-4 were extruded with atwin-screw kneading extruder to prepare the golf ball resin compositionsin a pellet form. The extruding conditions were a screw diameter of 45mm, a screw rotational speed of 200 rpm, and screw LID=35. The mixtureswere heated to 150 to 230° C. at the die position of the extruder. Theobtained golf ball resin composition was injection molded onto the coreobtained above to mold the intermediate layer (thickness: 1.0 mm).

TABLE 2 Golf ball No. 1 2 3 4 5 6 7 Inter- Golf Formula- Resin (A)Polyamide 15 20 40 40 40 40 40 mediate ball tion compo- resin 1 layerresin (Parts nent (B) Himilan — — — — — 10 10 compo- by AM7327 sitionmass) Himilan — — — — 30 — 20 AM7329 Himilan — — — — 30 — 30 AM7337Surlyn 42.5 40 30 30 — 20 — 9150 Surlyn 42.5 40 30 30 — 30 — 8150 (C)Organically 0.5 0.5 0.5 1 0.5 0.5 0.5 modified layered silicate AdditiveLOTADER — — — — — — — AX8840 Mg — — — — — — — stearate Stearic — — — — —— — acid Proper- Slab hardness (Shore D) 71 71 75 75 74 74 73 tiesFlexural modulus (MPa) 455 500 690 730 620 640 570 Rebound resilience(%) 54 54 53 53 51 52 51 MFR (240° C., 2.16 kgf) 16 14 11 11 12 11 12(g/10 min) Thickness (mm) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Golf Compressiondeformation amount (mm) 2.30 2.28 2.23 2.22 2.25 2.25 2.28 ballCoefficient of restitution 0.771 0.772 0.774 0.774 0.771 0.773 0.771Driver spin rate (rpm) 2460 2455 2440 2430 2435 2430 2445 Ball initialspeed (m/s) 73.66 73.66 73.72 73.73 73.64 73.69 73.63 Driver spin ratedifference (rpm) 40 45 60 70 65 70 55 Ball initial speed difference(m/s) 0.070 0.070 0.130 0.140 0.050 0.100 0.040 Flight distance (m)266.8 266.8 267.3 267.5 266.9 267.2 266.8 Golf ball No. 8 9 10 11 12 1314 Inter- Golf Formula- Resin (A) Polyamide 60 60 80 40 40 20 60 mediateball tion compo- resin 1 layer resin (Parts nent (B) Himilan — — — — — —— compo- by AM7327 sition mass) Himilan — 20 — — — — — AM7329 Himilan —20 — — — — — AM7337 Surlyn 20 — 10 30 30 40 20 9150 Surlyn 20 — 10 30 3040 20 8150 (C) Organically 0.5 0.5 0.5 0.5 0.5 0.5 0.5 modified layeredsilicate Additive LOTADER — — — — — — — AX8840 Mg — — — — — — — stearateStearic — — — 1 5 1 1 acid Proper- Slab hardness (Shore D) 76 75 78 7576 71 76 ties Flexural modulus (MPa) 830 780 1020 700 720 510 840Rebound resilience (%) 51 50 50 53 53 54 51 MFR (240° C., 2.16 kgf) 9.611 5.2 15 18 18 13 (g/10 min) Thickness (mm) 1.0 1.0 1.0 1.0 1.0 1.0 1.0Golf Compression deformation amount (mm) 2.19 2.21 2.16 2.23 2.22 2.282.19 ball Coefficient of restitution 0.773 0.769 0.770 0.774 0.774 0.7720.773 Driver spin rate (rpm) 2415 2450 2400 2435 2430 2450 2410 Ballinitial speed (m/s) 73.69 73.64 73.61 73.72 73.73 73.66 73.69 Driverspin rate difference (rpm) 85 50 100 65 70 50 90 Ball initial speeddifference (m/s) 0.100 0.050 0.020 0.130 0.140 0.070 0.100 Flightdistance (m) 267.4 266.8 267.0 267.4 267.5 266.9 267.4

TABLE 3 Golf ball No. 15 16 17 18 19 20 21 Inter- Golf Formula- Resin(A) Polyamide 10 15 20 40 40 40 40 mediate ball tion compo- resin 1layer resin (Parts nent (B) Himilan — — — — — 10 10 compo- by AM7327sition mass) Himilan — — — — 30 — 20 AM7329 Himilan — — — — 30 — 30AM7337 Surlyn 45 42.5 40 30 — 20 — 9150 Surlyn 45 42.5 40 30 — 30 — 8150(C) Organically — — — — — — — modified layered silicate Additive LOTADER— — — — — — — AX8840 Mg — — — — — — — stearate Stearic — — — — — — —acid Proper- Slab hardness (Shore D) 69 70 70 74 73 73 70 ties Flexuralmodulus (MPa) 370 400 450 630 560 580 480 Rebound resilience (%) 54 5353 52 50 51 49 MFR (240° C., 2.16 kgf) 17 16 14 11 12 11 12 (g/10 min)Thickness (mm) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Golf Compression deformationamount (mm) 2.33 2.31 2.30 2.24 2.26 2.26 2.29 ball Coefficient ofrestitution 0.769 0.769 0.769 0.771 0.768 0.771 0.766 Driver spin rate(rpm) 2490 2485 2480 2455 2460 2465 2480 Ball initial speed (m/s) 73.5873.59 73.59 73.62 73.55 73.62 73.52 Driver spin rate difference (rpm) 1015 20 45 40 35 20 Ball initial speed difference (m/s) −0.010 0.000 0.0000.030 −0.040 0.030 −0.070 Flight distance (m) 266.0 266.1 266.2 266.6266.1 266.5 265.7 Golf ball No. 22 23 24 25 26 27 Inter- Golf Formula-Resin (A) Polyamide 60 60 80 90 10 90 mediate ball tion compo- resin 1layer resin (Parts nent (B) Himilan — — — — — — compo- by AM7327 sitionmass) Himilan — 20 — — — — AM7329 Himilan — 20 — — — — AM7337 Surlyn 20— 10 5 45 5 9150 Surlyn 20 — 10 5 45 5 8150 (C) Organically — — — — 0.50.5 modified layered silicate Additive LOTADER — — — — — — AX8840 Mg — —— — — — stearate Stearic — — — — — — acid Proper- Slab hardness (ShoreD) 75 74 76 77 70 79 ties Flexural modulus (MPa) 710 680 880 1020 4201120 Rebound resilience (%) 51 49 49 47 55 48 MFR (240° C., 2.16 kgf) 1011 6.3 3.8 17 2.8 (g/10 min) Thickness (mm) 1.0 1.0 1.0 1.0 1.0 1.0 GolfCompression deformation amount (mm) 2.21 2.23 2.19 2.16 2.31 2.13 ballCoefficient of restitution 0.770 0.766 0.766 0.763 0.771 0.767 Driverspin rate (rpm) 2450 2430 2420 2400 2465 2385 Ball initial speed (m/s)73.61 73.49 73.50 73.44 73.65 73.55 Driver spin rate difference (rpm) 5070 80 100 35 115 Ball initial speed difference (m/s) 0.020 −0.100 −0.09−0.150 0.060 −0.040 Flight distance (m) 266.5 265.9 266.1 265.9 266.7266.7

TABLE 4 Golf ball No. 28 29 30 31 32 33 Inter- Golf Formula- Resin (A)Polyamide 40 60 60 — — — mediate ball tion compo- resin 2 layer resin(Parts nent Polyamide — — — 60 — — compo- by resin 3 sition mass) (B)Himilan — — — — — — AM7327 Himilan 30 20 20 20 — 50 AM7329 Himilan 30 2020 20 — 50 AM7337 Surlyn 9150 — — — — 50 — Surlyn 8150 — — — — 50 — (C)Organically — — — — — — modified layered silicate Additive LOTADER — — —5 — — AX8840 Mg stearate — — 5 — — — Stearic acid — — — — — — Proper-Slab hardness (Shore D) 68 69 70 68 69 65 ties Flexural modulus (MPa)495 639 653 500 350 290 Rebound resilience (%) 49 49 49 49 55 53 MFR(240° C., 2.16 kgf) 11 3.2 18 1.2 — — (g/10 min) Thickness (mm) 1.0 1.01.0 1.0 1.0 1.0 Golf Compression deformation amount (mm) 2.30 2.25 2.282.29 2.35 2.41 ball Coefficient of restitution 0.765 0.766 0.766 0.7660.770 0.763 Driver spin rate (rpm) 2500 2480 2475 2500 2500 2560 Ballinitial speed (m/s) 73.48 73.51 73.51 73.49 73.59 73.50 Driver spin ratedifference (rpm) 0 20 25 0 0 −60 Ball initial speed difference (m/s)−0.110 −0.080 −0.080 −0.100 0.000 −0.090 Flight distance (m) 265.3 265.6265.7 265.4 266.0 264.9

Materials used in Tables 2-4 are shown below.

-   Polyamide resin 1: AMILAN CM1017K (Polyamide 6, degree of    crystallinity: 7%, flexural modulus: 3.1 GPa (23° C. absolute dry),    relative viscosity: 2.65, melt flow rate (260° C., 325 gf): 8.27    g/min) manufactured by Toray Industries, Inc.-   Polyamide resin 2: NOVAMID ST120 which is a mixed resin of polyamide    6 and a resin having at least one functional group selected from the    group consisting of a hydroxyl group, a carboxyl group, an anhydride    group, a sulfonic acid group, and an epoxy group (including a    glycidyl group) (flexural modulus: 2,000 MPa, melt flow rate (240°    C., 2.16 kgf): 30 g/10 min) manufactured by Mitsubishi-Engineering    Plastics Company.-   Polyamide resin 3: NOVAMID ST220 which is a polyamide resin    (Polyamide 6, high impact-grade, flexural modulus: 2,000 MPa)    manufactured by Mitsubishi Engineering-Plastics Company.-   Himilan AM7327: Zinc ion neutralized ethylene-methacrylic acid-butyl    acrylate ternary copolymer ionomer resin (melt flow rate (190° C.,    2.16 kgf): 0.7 g/10 min, flexural modulus: 35 MPa, Shore D    hardness: 42) manufactured by Du Pont-Mitsui Polychemicals Co., Ltd.-   Himilan AM7329: Zinc ion neutralized ethylene-methacrylic acid    copolymer ionomer resin (melt flow rate (190° C., 2.16 kgf): 5 g/10    min, flexural modulus: 240 MPa, Shore D hardness: 62) manufactured    by Du Pont-Mitsui Polychemicals Co., Ltd.-   Himilan AM7337: Sodium ion neutralized ethylene-methacrylic acid    copolymer ionomer resin (melt flow rate (190° C., 2.16 kgf): 5 g/10    min, flexural modulus: 254 MPa, Shore D hardness: 64) manufactured    by Du Pont-Mitsui Polychemicals Co., Ltd.-   Surlyn 9150: Zinc ion neutralized ethylene-methacrylic acid    copolymer ionomer resin (content of acid component: 17 mass % or    more, flexural modulus: 270 MPa, melt flow rate (190° C., 2.16 kgf):    4.5 g/10 min, Shore D hardness: 64) manufactured by E.I. du Pont de    Nemours and Company.-   Surlyn 8150: Sodium ion neutralized ethylene-methacrylic acid    copolymer ionomer resin (content of acid component: 17 mass % or    more, flexural modulus: 390 MPa, melt flow rate (190° C., 2.16 kgf):    4.5 g/10 min, Shore D hardness: 68) manufactured by E.I. du Pont de    Nemours and Company.    (3) Molding of Half Shell

100 parts by mass of the polyurethane elastomer and 4 parts by mass oftitanium oxide shown in Table 5 were dry blended, and mixed with atwin-screw kneading extruder to obtain the cover compositions in apellet form. The extruding conditions were a screw diameter of 45 mm, ascrew rotational speed of 200 rpm, and screw LID=35. The mixtures wereheated to 150 to 230° C. at the die position of the extruder. Thecompression molding of half shells was carried out by charging theobtained cover composition in the pellet form into each concave portionof the lower mold for molding the half shells, and performingcompression to form the half shells. The compression molding wasperformed at the temperature of 170° C. for five minutes under thepressure of 2.94 MPa.

TABLE 5 Cover composition Formulation (Parts by mass) Elastollan XNY85A100 Titanium oxide 4 Slab hardness (Shore D) 32 Elastollan XNY85A:Thermoplastic polyurethane elastomer manufactured by BASF Ltd. (4)Molding of Cover

The intermediate layer obtained in (2) was covered concentrically withtwo half shells obtained in (3) and compression molded to form the cover(thickness: 0.5 mm). The compression molding was performed at thetemperature of 145° C. for two minutes under the pressure of 9.8 MPa.

On the surface of the golf balls, dimple patterns shown in Table 6, FIG.1 and FIG. 2 were formed. The northern hemisphere N and the southernhemisphere S of the golf balls have U units that are 120 degreerotational symmetrical to one another. The number of U units on each ofthe northern hemisphere N and the southern hemisphere S is 3. In FIG. 2,the dimple types of only one U unit are shown with simbols A to H.

TABLE 6 Curva- Diam- ture eter Depth radius Volume Front Plan TypeNumber (mm) (mm) (mm) (mm³) view view A 24 4.75 0.140 20.22 1.242 FIG. 1FIG. 2 B 18 4.65 0.140 19.38 1.190 C 30 4.55 0.135 19.24 1.099 D 42 4.450.135 18.40 1.051 E 66 4.25 0.135 16.79 0.959 F 126 4.05 0.130 15.840.839 G 12 3.95 0.130 15.07 0.798 H 12 2.80 0.120 8.23 0.370

The surface of the obtained golf ball body was treated with sandblast,marked, and painted with a clear paint. The paint was dried in an ovenat 40° C. and golf balls having a diameter of 42.7 mm and a mass of 45.3g were obtained. The evaluation results with respect to the obtainedgolf balls were shown in Tables 2-4.

The golf balls No. 1 to No. 14 are the case that the intermediate layerthereof is formed from a golf ball resin composition containing: (A) apolyamide resin, (B) at least one member selected from the groupconsisting of (b-1) a binary copolymer composed of an olefin and anα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (b-2) ametal ion-neutralized product of a binary copolymer composed of anolefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbonatoms, (b-3) a ternary copolymer composed of an olefin, anα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and anα,β-unsaturated carboxylic acid ester, and (b-4) a metal ion-neutralizedproduct of a ternary copolymer composed of an olefin, an α,β-unsaturatedcarboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturatedcarboxylic acid ester, and (C) an organically modified layered silicate,wherein a mass ratio ((A)/(B)) of (A) component to (B) component rangesfrom 15/85 to 80/20. It is apparent that these golf balls travel a greatflight distance on driver shots.

The resin composition of the present invention is appropriate as a resincomposition for constituting a golf ball. This application is based onJapanese Patent application No. 2013-224606 filed on Oct. 29, 2013, thecontent of which are hereby incorporated by reference.

Description of Symbol

A, B, C, D, E, F, G, H: dimple, N: northern hemisphere, P: pole, S:southern hemisphere, U: unit

The invention claimed is:
 1. A golf ball resin composition having a slabhardness of 69 or more in Shore D hardness and consisting of: (A) apolyamide resin, (B) at least one member selected from the groupconsisting of (b-1) a binary copolymer composed of an olefin and anα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (b-2) ametal ion-neutralized product of a binary copolymer composed of anolefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbonatoms, (b-3) a ternary copolymer composed of an olefin, anα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and anα,β-unsaturated carboxylic acid ester, and (b-4) a metal ion-neutralizedproduct of a ternary copolymer composed of an olefin, an α,β-unsaturatedcarboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturatedcarboxylic acid ester, (C) an organically modified layered silicate inan amount of 0.1 parts by mass to 50 parts by mass with respect to 100parts by mass of a total of (A) component and (B) component, and a fattyacid and/or a metal salt of a fatty acid, wherein a mass ratio ((A)/(B))of (A) component to (B) component ranges from 15/85 to 80/20, (C) theorganically modified layered silicate includes a layered silicatetreated with an organic onium ion, and the organic onium ion includes anorganic ammonium ion having a total of 11 to 30 intramolecular carbonatoms.
 2. The golf ball resin composition according to claim 1, whereinthe content of the α,β-unsaturated carboxylic acid having 3 to 8 carbonatoms in (B) component is 16 mass % or more.
 3. The golf ball resincomposition according to claim 1, wherein the golf ball resincomposition has a slab hardness ranging from 69 to 80 in Shore Dhardness.
 4. The golf ball resin composition according to claim 1,wherein the golf ball resin composition has a flexural modulus rangingfrom 400 MPa to 4,000 MPa.
 5. The golf ball resin composition accordingto claim 1, wherein the golf ball resin composition has a reboundresilience of 48% or more.
 6. A golf ball comprising a core, at leastone intermediate layer covering the core, and a cover covering theintermediate layer, wherein at least one of the core, at least oneintermediate layer or cover is formed from a golf ball resin compositionhaving a slab hardness of 69 or more in Shore D hardness and consistingof: (A) a polyamide resin, (B) at least one member selected from thegroup consisting of (b-1) a binary copolymer composed of an olefin andan α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (b-2) ametal ion-neutralized product of a binary copolymer composed of anolefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbonatoms, (b-3) a ternary copolymer composed of an olefin, anα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and anα,β-unsaturated carboxylic acid ester, and (b-4) a metal ion-neutralizedproduct of a ternary copolymer composed of an olefin, an α,β-unsaturatedcarboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturatedcarboxylic acid ester, (C) an organically modified layered silicate inan amount of 0.1 parts by mass to 50 parts by mass with respect to 100parts by mass of a total of (A) component and (B) component, and a fattyacid and/or a metal salt of a fatty acid, wherein a mass ratio ((A)/(B))of (A) component to (B) component ranges from 15/85 to 80/20, (C) theorganically modified layered silicate includes a layered silicatetreated with an organic onium ion, and the organic onium ion includes anorganic ammonium ion having a total of 11 to 30 intramolecular carbonatoms.
 7. The golf ball according to claim 6, wherein the content of theα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms in (B)component is 16 mass % or more.
 8. The golf ball according to claim 6,wherein the golf ball resin composition has a slab hardness ranging from69 to 80 in Shore D hardness.
 9. The golf ball according to claim 6,wherein the golf ball resin composition has a flexural modulus rangingfrom 400 MPa to 4,000 MPa.
 10. The golf ball according to claim 6,wherein the golf ball resin composition has a rebound resilience of 48%or more.
 11. A golf ball resin composition consisting of: (A) apolyamide resin, (B) at least one member selected from the groupconsisting of (b-1) a binary copolymer composed of an olefin and anα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (b-2) ametal ion-neutralized product of a binary copolymer composed of anolefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbonatoms, (b-3) a ternary copolymer composed of an olefin, anα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and anα,β-unsaturated carboxylic acid ester, and (b-4) a metal ion-neutralizedproduct of a ternary copolymer composed of an olefin, an α,β-unsaturatedcarboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturatedcarboxylic acid ester, (C) an organically modified layered silicate, anda fatty acid and/or a metal salt of a fatty acid, wherein a mass ratio((A)/(B)) of (A) component to (B) component ranges from 15/85 to 80/20,and a slab hardness of the golf ball resin composition is 69 or more inShore D hardness.
 12. The golf ball resin composition according to claim11, wherein (C) the organically modified layered silicate includes alayered silicate treated with an organic ammonium ion, and the organicammonium ion includes at least one selected from the group consisting ofdecyl ammonium ion, dodecyl ammonium ion, oleyl ammonium ion, and benzylammonium ion; methyl dodecyl ammonium ion and methyl octadecyl ammoniumion; dimethyl dodecyl ammonium ion and dimethyl octadecyl ammonium ion;benzyl trimethyl ammonium ion, benzyl triethyl ammonium ion, benzyltributyl ammonium ion, benzyl dimethyl dodecyl ammonium ion, benzyldimethyl octadecyl ammonium ion, trioctyl methyl ammonium ion, trimethyloctyl ammonium ion, trimethyl dodecyl ammonium ion, trimethyl octadecylammonium ion, and dimethyl didodecyl ammonium ion; aniline ion,p-phenylene diamine ion, α-naphthylamine ion, p-aminodimethyl anilineion, benzidine ion, pyridine ion, piperidine ion, 6-aminocaproic acidion, 11-aminoundecanoic acid ion, and 12-aminododecanoic acid ion.
 13. Agolf ball comprising a core, at least one intermediate layer coveringthe core, and a cover covering the intermediate layer, wherein at leastone of the core, at least one intermediate layer or cover is formed froma golf ball resin composition consisting of: (A) a polyamide resin, (B)at least one member selected from the group consisting of (b-1) a binarycopolymer composed of an olefin and an a α,β-unsaturated carboxylic acidhaving 3 to 8 carbon atoms, (b-2) a metal ion-neutralized product of abinary copolymer composed of an olefin and an α,β-unsaturated carboxylicacid having 3 to 8 carbon atoms, (b-3) a ternary copolymer composed ofan olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atomsand an α,β-unsaturated carboxylic acid ester, and (b-4) a metalion-neutralized product of a ternary copolymer composed of an olefin, anα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and anα,β-unsaturated carboxylic acid ester, (C) an organically modifiedlayered silicate, and a fatty acid and/or a metal salt of a fatty acid,wherein a mass ratio ((A)/(B)) of (A) component to (B) component rangesfrom 15/85 to 80/20, and a slab hardness of the golf ball resincomposition is 69 or more in Shore D hardness.
 14. The golf ballaccording to claim 13, wherein (C) the organically modified layeredsilicate includes a layered silicate treated with an organic ammoniumion, and the organic ammonium ion includes at least one selected fromthe group consisting of decyl ammonium ion, dodecyl ammonium ion, oleylammonium ion, and benzyl ammonium ion; methyl dodecyl ammonium ion andmethyl octadecyl ammonium ion; dimethyl dodecyl ammonium ion anddimethyl octadecyl ammonium ion; benzyl trimethyl ammonium ion, benzyltriethyl ammonium ion, benzyl tributyl ammonium ion, benzyl dimethyldodecyl ammonium ion, benzyl dimethyl octadecyl ammonium ion, trioctylmethyl ammonium ion, trimethyl octyl ammonium ion, trimethyl dodecylammonium ion, trimethyl octadecyl ammonium ion, and dimethyl didodecylammonium ion; aniline ion, p-phenylene diamine ion, α-naphthylamine ion,p-aminodimethyl aniline ion, benzidine ion, pyridine ion, piperidineion, 6-aminocaproic acid ion, 11-aminoundecanoic acid ion, and12-aminododecanoic acid ion.
 15. A golf ball resin compositioncomprising: (A) a polyamide resin, (B) at least one member selected fromthe group consisting of (b-1) a binary copolymer composed of an olefinand an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (b-2)a metal ion-neutralized product of a binary copolymer composed of anolefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbonatoms, (b-3) a ternary copolymer composed of an olefin, anα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and anα,β-unsaturated carboxylic acid ester, and (b-4) a metal ion-neutralizedproduct of a ternary copolymer composed of an olefin, an α,β-unsaturatedcarboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturatedcarboxylic acid ester, (C) an organically modified layered silicate, anda fatty acid and/or a metal salt of a fatty acid, wherein a mass ratio((A)/(B)) of (A) component to (B) component ranges from 15/85 to 80/20,and a slab hardness of the golf ball resin composition is 76 or more inShore D hardness.
 16. A golf ball comprising a core, at least oneintermediate layer covering the core, and a cover covering theintermediate layer, wherein at least one of the core, at least oneintermediate layer or cover is formed from a golf ball resin compositioncomprising: (A) a polyamide resin, (B) at least one member selected fromthe group consisting of (b-1) a binary copolymer composed of an olefinand an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (b-2)a metal ion-neutralized product of a binary copolymer composed of anolefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbonatoms, (b-3) a ternary copolymer composed of an olefin, anα,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and anα,β-unsaturated carboxylic acid ester, and (b-4) a metal ion-neutralizedproduct of a ternary copolymer composed of an olefin, an α,β-unsaturatedcarboxylic acid having 3 to 8 carbon atoms and an α,β-unsaturatedcarboxylic acid ester, (C) an organically modified layered silicate, anda fatty acid and/or a metal salt of a fatty acid, wherein a mass ratio((A)/(B)) of (A) component to (B) component ranges from 15/85 to 80/20,and a slab hardness of the golf ball resin composition is 76 or more inShore D hardness.